Over the last thirty years, improvements to transformation methodologies have resulted in increased transformation efficiency of soybeans. As a result, agronomically valuable traits may be routinely incorporated into the soybean genome. For example, new transgenic soybean products, such as Enlist™ soybeans, are commercially available throughout the world and offer improved solutions for ever-increasing challenges caused by weeds. Such innovative products would not be possible but for development and improvement of soybean transformation methodologies. New and improved soybean transformation methodologies that can be utilized to detect and select soybean germline transformants at early stages within the soybean transformation process are important for continuing to improve the efficiency of the soybean transformation process.
The early identification and selection of soybean germline transformants in a transformation process is highly desirable because these soybean germline transformants comprise a stably integrated transgene which is heritable in subsequent generations. However, due to the relative inefficiencies of the transformation process, large numbers of transformants must be produced in order to identify and to select-desirable soybean germline transformants from the undesirable soybean non-germline transformants. On average, about 40 to 70 percent of all isolated transformants are undesirable soybean non-germline transformants, such as chimeric or soybean non-germline transformants, which must be “culled” (i.e., discarded) in favor of the desirable soybean germline transformants. However, using traditional methods, the process of culling occurs only after the transformants are maintained throughout the transformation process and have advanced to maturity. Using traditional methods, the maintenance of undesirable transformants, such as non-germline soybean transformants, results in an inefficient use of resources and an undesirable increase in cost expended to produce transgenic plants from the non-germline transformants. Such costs exceed pecuniary concerns and include the use of scientists' time, materials, and laboratory space. The present disclosure provides methods that exhibit desirable properties and provides related advantages for identification and selection of soybean germline transformants. The present disclosure demonstrates that the identification and selection of soybean germline transformants at the early stages of the plant transformation can be accomplished using a selective rooting medium containing a selection agent. Through use of the selective rooting medium, undesirable chimeric or soybean non-germline transformants can be culled without the requirement of maintenance throughout the transformation process and without advancing through maturity. As a result, the production of transgenic plants may be more efficient, and an improvement in allocating resources to produce transgenic plants may be realized.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification.